The distance between Party A and Party B is 80km. The express and local trains go from place a to place B at the same time. The express train arrives 20 minutes earlier than the local train. The speed of the fast and local trains is 4:3, so the speed of the local train is more The fast to slow ratio is 4:3, so what's the slow speed?

The distance between Party A and Party B is 80km. The express and local trains go from place a to place B at the same time. The express train arrives 20 minutes earlier than the local train. The speed of the fast and local trains is 4:3, so the speed of the local train is more The fast to slow ratio is 4:3, so what's the slow speed?

20 minutes = 1 / 3 hour
If the slow speed is set to 3x, the fast speed is set to 4x
80÷（3x）-80÷（4x）=1/3
x=20
Idle speed = 20 × 3 = 60 km

The speed of the fast train is 45km and that of the slow train is 20km. After the two trains meet for three times, the fast train runs 360km to meet each other
The speed of the fast train is 45km and that of the slow train is 20km. After the two trains meet for three times, the fast train runs 360km and then meets the slow train, so as to find the whole journey

Time to meet again = 360 △ 45 = 8 hours
The total time of the fourth encounter = 8 × 3 + 8 △ 2 = 28 hours
Whole journey = 28 × (45 + 20) △ 1 + 2 × 3) = 260 km